1. Field of Invention
This invention relates to microelectromechanical system (MEMS)xe2x80x94based fluid ejectors or micromachined fluid ejectors.
2. Description of the Related Art
Fluid ejectors have been developed for ink jet recording or printing. Ink jet recording apparatuses offer numerous benefits, including extremely quiet operation when recording, high speed printing, a high degree of freedom in ink selection, and the ability to use low-cost plain paper. In the so-called xe2x80x9cdrop-on-demandxe2x80x9d(hive method, which is now the conventional approach, ink is output only when required for recording. The drop-on-demand drive method makes it unnecessary to recover ink not needed for recording.
Fluid ejectors for ink jet printing include one or more nozzles which allow the formation and control of small ink droplets to permit high resolution, resulting in the ability to print sharper characters with improved tonal resolution. In particular, drop-on-demand ink jet printheads are generally used for high resolution printers.
Drop-on-demand technology generally uses some type of pulse generator to form and eject the ink drops. For example, in one type of ink jet printhead, a chamber having an ink nozzle may be fitted with a piezoelectric wall that is deformed when a voltage is applied. As a result of the deformation, a drop of the fluid is forced out of the nozzle orifice and impinges directly on an associated printing surface. Use of such a piezoelectric device as a nozzle driver is described in JP B-1990-51734.
Another type of printhead uses bubbles formed by heat pulses to force fluid out of the nozzle. The drops are separated from the ink supply when the bubbles collapse. Use of pressure generated by heating the ink to generate bubbles is described in JP B-1986-59911.
Yet another type of xe2x80x9cdrop-on-demandxe2x80x9dprinthead incorporates an electrostatic actuator. This type of printhead utilizes electrostatic force to eject the ink. Examples of such electrostatic print heads are discussed in U.S. Pat. No. 5,754,205 to Miyata et al., U.S. Pat. No. 4,520,375 to Kroll and Japanese Laid-Open Patent Publication No. 289351/90, each incorporated herein by reference. The ink jet printhead discussed in the 375 patent uses an electrostatic actuator comprising a diaphragm that constitutes a part of an ink ejection chamber and a base plate disposed outside of the ink ejection chamber opposite the diaphragm. The ink jet printhead ejects fluid droplets through a nozzle in communication with the ejection chamber by applying a time-varying voltage between the diaphragm and the base plate. The diaphragm and the base plate thus act as a capacitor that causes the diaphragm to be set into mechanical motion and a drop of the fluid to exit the ejection chamber in response to the diaphragm motion. On the other hand, the ink jet printhead discussed in Japan 351 distorts its diaphragm by applying voltage to an electrostatic actuator fixed on the diaphragm. This result in suction of fluid into the ejection chamber. Once the voltage is removed, the diaphragm is restored to its non-distorted condition, ejecting the fluid from the ejection chamber.
Fluid drop ejectors may be used not only for printing, but also for depositing photoresist and other liquids in the semiconductor and flat panel display industries, for delivering drug and biological samples, for delivering multiple chemicals for chemical reactions, for handling DNA sequences, for delivering drugs and biological materials for interaction studies and assaying, and for depositing thin and narrow layers of plastics for usable as permanent and/or removable gaskets in micro-machines.
As noted above, fluid jet ejectors typically use thermal actuation, piezoelectric actuation, or, in the case of the fluid jet ejector disclosed in the 205 patent, electrostatic actuation, to eject drops. These types of actuation may involve drawbacks for certain applications. For example, piezoelectric actuators require multi-step very-small-scale assembly involving forming and attaching the piezoelectric material into an ejector assembly. In addition, the resulting piezoelectric actuator assembly is too large for efficient, dense packing. Thermal actuators require a relatively large amount of energy and can only produce drops of a single size. Electrostatic actuators have the potential for compact, integrated, monolithic fabrication (i.e., little or no assembly required) with drop size modulation. Electrostatic actuators, however, are sensitive to the electrical properties of the fluid, including the dielectric constant, the breakdown voltage, and the conductivity of the fluid, as the fluid is effectively part of the actuation system.
This invention provides systems and methods that enable a high performance fluid ejection driver.
This invention separately provides a fluid ejection driver that can be manufactured with lower cost.
This invention separately provides fluid ejection drivers that operate independently of the fluid to be ejected.
This invention separately provides fluid ejection drivers that are able to modulate the drop size on demand.
This invention separately provides fluid ejection drivers that are able to operate with a reduced applied drive voltage.
This invention separately provides magnetic fluid ejection drivers.
This invention further provides magnetic fluid ejection drivers that use a current loop.
This invention separately provides magnetic fluid ejection drive using a magnetic material.
This invention separately provides magnetic fluid ejection drivers that include a permanently magnetized material.
This invention separately provides magnetic fluid ejection drivers in which a strong magnetic field is produced for a given applied current.
This invention separately provides magnetic fluid ejection drivers in which a given magnetic field is produced by a reduced applied current.
This invention separately provides magnetic fluid ejection drivers in which a movable member is driven by a repulsive magnetic force.
This invention separately provides magnetic fluid ejection drivers in which a movable member is driven by an attractive magnetic force.
This invention separately provides a micromachined fluid ejector in which the foregoing drawbacks are reduced, if not eliminated.
In various exemplary embodiments of the systems and methods of this invention, magnetic forces are used to drive a movable member of a fluid ejector. Various exemplary embodiments include at least one primary current coil to which a drive signal is applied. Various exemplary embodiments use magnetic materials, permanently magnetized materials, permanent magnets and/or secondary coils to achieve a desired magnetic field within the fluid ejector. In various exemplary embodiments, the permanently magnetized material is a permanent magnet.
In various exemplary embodiments, the magnetic fluid ejection driver uses only one controlled current. In various other exemplary embodiments, the magnetic fluid ejection driver uses two controlled currents. In still other various exemplary embodiments, the magnetic fluid ejection driver uses an induced secondary current.
In various exemplary embodiments, the magnetic fluid ejection driver controllably moves a movable member of the fluid ejector in a single direction. In various other exemplary embodiments, the magnetic fluid ejection driver controllably moves the movable member in two opposite directions.
In various exemplary embodiments, the movable member ejects fluid when driven. In various other exemplary embodiments, the movable member ejects fluid after being driven.
These and other features and advantages of this invention are described in, or are apparent from, the following detailed description of various exemplary embodiments of the systems and methods of this invention.